Thermometer



Nov. 14, 1939. c, R, P LMER 2,180,285

THERMOMETER Filed Jan. 24, 1958 ywbuf EZV NTQR.

BY wmzwmz ATTORNEY. S

Patented Nov. 14, 1939 I 2,180,285 THERMOMETER .Charles R. Palmer, Glen Acres, Ohio, assignor to 1 The Palmer Company, Norwood, Ohio, a corporation of Ohio Application Januaryjfi, 1938, SerialiNo. 186,503

v 3 Claims. 7 (01. 73-37;)

This invention relates to thermometers and has particular application to a thermometer that is used for a purpose which permits the indication of a temperature within a certain zone 1 or range, rather than in exact degrees or frac-.

tions thereof.

One object of my invention has been to provide a thermometer which will quickly, and certainly,

disclose whether a particular temperature is Within a certain comparatively broad range,

rather than within a certain degree or-fraction ofadegree. e

A second object of my invention has been to provide a thermometer adapted for useunder particular conditions. Throughout this application the ordinary domestic ice box, or electric refrigerator, will be treatedas a typical example of the conditions under which the thermometerof my inventionis particularly adapted to be used. I

A third object of my invention has been to provide a thermometer which .will indicate vari- 1 ous ranges of temperature-by means of a reflecdegrees on a conventional graduated scale.

Other objects and purposes will be apparent in the further and more detailed description of my invention, in which: I

Figure 1 isa' front elevation of a thermometer of the general type of my invention with the mercury advanced partially through the centercolor range of a series of-three such ranges.

Figure 2 is a cross-section along the line 2-2, Figure 1. v

Figure Bis the same thermometer, still in reading position, and with the mercury advanced only partially through the range of the first color.

In Figure 4, the mercury has advanced to the top of the highest color section.

The invention is disclosed in relation to a mercury column in a glass tube, since these are the elements which are conventionally used in making the more accurate thermometers; although it must be understood that the invention may be used with other transparencies and other liquid columns, including some which are in use at the present time, as well as others which may be developed subsequently.

The type of thermometers to which the invention has, a particular application disclosed in the United States patent to, Palmer et alt,

No." 1,819,919, issued August 18, 1931. The ther- ,mometers of thispatent comprise a bulbconstituting 'a reservoir for ,mercury, and :a-stem or 1 tube having a bore within, which the mercury can expand to varying levels to indicate temperature. According to the patent, the mercury iiects light from a stripe or color extending substantially parallel to the bore of thetubei- The color stripe is disposed so as to be reflected by the column of mercury through the reading face of the'tube. A backing, or curtain,behind the mercury column, is provided to facilitate differ entiation of the color reflected by the column. The stem is configurated to constitute amagnifying lens in order to facilitate reading of the temperature indication, and. the stripefmay be shielded, or concealed further to facilitate the reading. r I

-Theordinary-thermometer, including those of the type-disclosed in the aforesaid patent to Palmer etal. is, graduated for reading tempera tures in degrees or fractions of degrees Although such accuracy of reading is probably essential in the case of thermometers and many types of in.- dustrial thermometers, there. are many purposes for which a'thermometer may be used, where extreme accuracy is not essential; ,An example column constitutes-a mirror surface which reof this wouldbe a thermometer which-is placed sirableto provide a thermometer -'fromjwhich temperature canbedetermined with-a maximum of ease. I Referring specifically to Figure 2 of the drawing, a thermometer tube is indicated at 15. The

tube is so shaped in cross section that the reading face constitutes a lens adapted to magnify the bore I6 or an image of the liquid in the bore. The bore isof oblong configuration and includes a flat surface or panel disposed at an angle to the reading face or lens, so. as to reflect the imageof the color stripe H which is located at for the colors, the white curtain I8 is provided):

in the tube directly behind the bore. This curtain is of translucent material in order topermit the entry of light from the rear of the tube.

In installations where the usual light inside the refrigerator is to be utilized, the light enters through the open portion of the base piece of the casing and illuminates the color stripe in this manner.

One of the concepts of the present invention is to constitute the column of mercury a mirror surface which will reflect different colors to indicate temperatures within particular ranges. Various different colors respectively confined to predetermined temperature ranges may be re flected from a vari-colored stripe, properly po- "sitioned in relation to the bore in the thermometer tubing. The principle of the reflecting mercury column is disclosed in the aforesaid patent to Palmer et al. The color column is composed of a plurality of color sections, one above the other, each color section extending over a particular, predetermined temperature range.

In reading the thermometer, the colors are reflected from the mirror surface up to a point equal to the height of the mercury in the bore. The uppermost color so reflected denotes the temperature range.

A particular application of the invention would be a thermometer having a color column of three colors and designed for use in a domestic ice box or refrigerator. Assuming the use of the colors yellow, green; and red, positioned respectively one over the other, the yellow might indicate a freezing temperature, such as one below 30 to 32 F., the green, safe refrigerator temperature zone, and the red, a temperature above the zone of safety. 1

Another application of the invention is a clinical thermometer in which all temperatures under fever heat are indicated by a more or less neutral color such as silver or yellow, and temperatures above fever heat, by another color such as red. In this application a conventional reading scale may serve as the primary temperature indicator.

As the mercury rises in the bore, the first color to be reflected will be that which is lowest on the stripe. As it continues to rise, the second lowermost color will also appear, and subsequently the third, so that when the mercury column has reached the top of the bore, all three colors will be apparent. When it is entirely confined in the bulb, none of the colors will be visible.

,the back of the refrigerator is apparent.

'be positioned toward the interior of the refrigerator, rather than adjacent to the door, where it would be more frequently subjected to the influence of the temperature of the room whenever the door is opened. The difficulty of reading degrees on a thermometer located toward On the other handQif the thermometer tube be visible at all, the reading of colors is a comparatively simple matter. I a

Other uses to which the thermometer of my invention would be particularly adapted would be any conventional thermometer use in which an exact reading of temperature is not required, or in which it is dificult to get sufliciently close to the thermometer to observe the degree reading.

Having described my invention, I claim:

1. In a thermometer, a tube having a longitudinal bore therein and a color stripe comprising a plurality of color sections positioned on the tube parallel to the bore, said bore having a flattened surface and being'so inclined with respect to the reading face of the thermometer and so oriented to the color stripe that a reflective and thermally expansive fluid rising in the bore will reflect the color sections successively through the reading face.

2. A thermometer comprising a tube having a longitudinal bore therein, a reading face on said tube, a bulb for containing a reflective and.

thermally expansive fluid, and a color stripe comprising a. plurality of color sections positioned on the tube parallel to the bore; said bore having a flattened surface so inclined with respect to the reading face and so oriented to the color stripe surface that the reflective and thermally expansive fluid rising in the bore will reflect the color sections successively through the read CHARLES R. PALMER. 

